CN107152956B - Contact-free level measuring system - Google Patents

Abstract

The invention provides a non-contact liquid level measurement system, which includes a light emitting cavity and a CCD receiving cavity, the light emitting cavity has an exit collimation slit of the light emitting cavity, and the CCD receiving cavity has a CCD The receiving cavity enters the collimation slit. When the non-contact liquid level measurement system is working, the light emitted by the luminous body in the light emitting cavity passes through the light emitting cavity and exits the collimation slit, and passes through the CCD receiving cavity and enters the collimation slit. This optical path enters the CCD receiving cavity and is received by the CCD. The sample tube is on the optical path and the light passes through the sample tube in a direction parallel to the generatrix of the sample tube. The sample tube can be clamped by the light emitting cavity and the CCD receiving cavity. The structure is compact and small, easy to install and disassemble, and has wide applicability. It can be used indoors or outdoors; non-contact measurement method, suitable for high pressure, flammable and explosive Liquid level detection in workplaces with high toxicity and high purity requirements.

Description

Non-contact liquid level measurement system

technical field

The invention relates to the field of automation, in particular to a non-contact liquid level measuring system. (This application is a divisional application with application number: 201410451333.6)

Background technique

The height of the liquid working medium in the container and its change over time are important technical parameters that must be monitored/detected in many jobs. There are already many methods and technologies for liquid level measurement, which can be roughly divided into two categories: contact and non-contact. The advantage of the non-contact measurement method is self-evident because it does not directly contact with the liquid working medium. Light waves, ultrasonic waves and even radioactive isotopes are commonly used methods for non-contact liquid level measurement. However, in the process of realization, it needs to be measured by a light-tight non-contact liquid level measuring device, which requires corresponding precision instruments for accurate measurement, which is a technical problem urgently needed to be solved by those skilled in the art.

Contents of the invention

The present invention aims at at least solving the technical problems existing in the prior art, and particularly innovatively proposes a non-contact liquid level measurement system.

In order to achieve the above purpose of the present invention, the present invention provides a non-contact liquid level measurement system, the key of which is to include a light emitting cavity 6 and a CCD receiving cavity 14, and the light emitting cavity 6 has a light emitting cavity The body exits the collimation slit 8, and the CCD receiving cavity 14 has a CCD receiving cavity incident collimating slit 16. When the non-contact liquid level measurement system is working, the light emitted by the illuminant in the light emitting cavity 6 passes through The light-emitting cavity exits the collimation slit 8, and enters the collimation slit 16 through the CCD receiving cavity. Orientation through the sample tube.

The beneficial effects of the above technical solution are: the sample tube can be clamped through the light emitting cavity 6 and the CCD receiving cavity 14, the structure is compact and small, the portability is strong, the degree of automation is high, the installation and disassembly are easy, and it has wide applicability. Or it can be used outdoors; non-contact measurement method, suitable for liquid level detection in workplaces with high pressure, flammable, explosive, high toxicity and high purity requirements.

The non-contact liquid level measurement system preferably includes: a sample tube clamping arm, a clamping end, a hinge 3, a light emitting cavity 6, a CCD receiving cavity 14, and a rear cover of the CCD receiving cavity 15. The output collimation slit of the light emitting cavity 8, the input collimation slit of the CCD receiving cavity 16;

One end of the sample tube clamping arm is vertically fixed on the side wall of the hinge 3, and the other end of the sample tube clamping arm is provided with a clamping end, and the clamping end tightly clamps the sample tube 1, and the right leaf of the hinge 3 The leaf 21 is equipped with a light emitting cavity 6, and the left fan blade 20 of the hinge 3 is equipped with a CCD receiving cavity 14, and the rear end of the CCD receiving cavity 14 is covered by the rear cover of the CCD receiving cavity to prevent light leakage; The middle part of the side panel of the light emitting cavity 6 clamping the sample tube is in the shape of a groove, and an exit collimation slit 8 of the light emitting cavity is set along the groove shape, and the CCD receiving cavity 14 clamps the side panel of the sample tube The middle part is also in the shape of a groove, along which a CCD receiving cavity incident collimation slit 16 is set.

The beneficial effect of the above technical solution is: the liquid level of the sample tube is detected through the light emitting cavity exiting the collimating slit 8 and the CCD receiving cavity entering the collimating slit 16, which ensures the accuracy of detection and prevents light scattering , deflection.

In the non-contact liquid level measurement system, preferably, the sample tube clamping arm includes: sample tube upper clamping arm 2, sample tube lower clamping arm 9, upper clamping arm locking screw 4, lower clamping arm Holding arm locking screw 10, upper casing 28, lower casing 29;

The clamping end includes: the upper locking screw 5 of the sample tube, the lower locking screw 11 of the sample tube, the upper clamping end 12 and the lower clamping end 13;

The outer interference sleeve of the upper clamping arm 2 of the sample tube is connected to one end of the upper sleeve 28, and the side wall of the upper sleeve 28 is provided with a threaded hole, and the locking screw 4 of the upper clamping arm is screwed into the threaded hole, and the upper clamp The external thread of the locking screw 4 of the arm is matched with the internal thread of the threaded hole to lock the upper sleeve 28 and the upper clamping arm 2 of the sample tube. The other end of the upper sleeve 28 is fixed to the upper clamping end 12. A threaded hole is provided on the side wall of the holding end 12, and the locking screw 5 on the upper part of the sample tube is screwed into the threaded hole. sample tube 1;

The outer interference sleeve of the lower clamping arm 9 of the sample tube is connected to one end of the lower casing 29, and the side wall of the lower casing 29 is provided with a threaded hole, and the locking screw 10 of the lower clamping arm is screwed into the threaded hole, and the lower clamping The external thread of the arm-holding locking screw 10 is matched with the internal thread of the threaded hole to lock the lower casing 29 and the lower clamping arm 9 of the sample tube. Threaded holes are provided on the side wall of the terminal 13, and the locking screw 11 at the lower part of the sample tube is screwed into the threaded hole. Tube 1.

The beneficial effect of the above technical solution is: the above device is used to lock the sample tube, while ensuring that the sample tube is perpendicular to the bottom surface up and down, ensuring accurate measurement.

The non-contact liquid level measurement system preferably further includes: an anti-light shielding sheet 7;

The light emitting cavity 6 is installed with an anti-light shielding baffle 7 at the edge of the other end side plate of the hinge, or an anti-light shielding plate 7 is installed at the edge of the other end side plate of the hinge at the CCD receiving cavity 14 . The light-shielding mask 7 protrudes from the edge of the side plate to cover the gap where the light-emitting cavity 6 and the CCD receiving cavity 14 are joined.

The beneficial effect of the above-mentioned technical solution is: the gap between the light emitting cavity and the CCD receiving cavity 14 is blocked by the blocking effect of the light-proof blocking sheet 7, so that the external light cannot be injected, thereby ensuring the accuracy of the measurement .

In the non-contact liquid level measurement system, preferably, the hinge 3 includes: a calibration hole 23, a first calibration screw 26, and a second calibration screw 27;

The left fan blade 20 of the hinge 3 and the right fan blade 21 of the hinge 3 respectively have N calibration holes 23, and the first calibration screw 26 and the second calibration screw 27 penetrate the calibration holes 23 and screw into the side plate, according to the sample The diameter of the tube 1 is adjusted by the first calibration screw 26 and the second calibration screw 27 so that the light emitting cavity 6 and the CCD receiving cavity 14 can receive the optical feedback data smoothly, and the said N≥2.

The beneficial effect of the above technical solution is that calibration holes and calibration screws are provided on one side of the hinge where the light emitting cavity and the CCD receiving cavity are installed, so that the light emitting cavity and the CCD can be easily adjusted according to the diameter of the sample tube. The width of the gap clamped between the receiving cavities.

In the non-contact liquid level measurement system, preferably, the light emitting cavity 6 includes: a light emitting circuit board 17,

The CCD receiving cavity 14 includes: a linear array CCD18 and a CCD receiving circuit board 19;

The light-emitting circuit board 17 is installed inside the light-emitting cavity 6, and the light information emitted by the light-emitting circuit board 17 passes through the output collimation slit 8 of the light-emitting cavity, and the linear array of the CCD receiving cavity 14 CCD18 is arranged at the incident collimation slit 16 of the CCD receiving cavity to receive optical information data, and the linear array CCD is connected to the CCD receiving circuit board 19;

Described CCD receiving circuit board 19 comprises: front-end drive data acquisition module AFE, FPGA, data transmission interface, control module;

The front-end driving data acquisition module AFE is connected to the linear array CCD, receives the optical information data transmitted by the linear array CCD, and completes double sampling and AD conversion of the analog CCD image signal; the other end of the front-end driving data acquisition module AFE is connected to the FPGA, and the The FPGA connects the data transmission interface and the control module.

The beneficial effect of the above technical solution is: through the design of the above circuit, the liquid level of the sample tube can be accurately measured by means of electron optics, thereby reducing the error of manual measurement and ensuring the accuracy of measurement.

In the non-contact liquid level measurement system, preferably, the shape of the groove includes: trapezoidal or semicircular.

The beneficial effects of the above technical solution are: the trapezoidal groove is set to ensure that the light emitting cavity and the CCD receiving cavity can better hold the sample tube, and the semicircle is set to ensure that the groove and the sample tube are tightly fitted , increase the coefficient of friction to ensure that the sample tube clamped by the light emitting cavity and the CCD receiving cavity is not easy to fall off.

The invention also discloses a non-contact liquid level measurement method, the key of which is to include the following steps:

Step 1, initialize the linear array CCD and CCD receiving circuit board of the non-contact liquid level measurement system, and start measuring the liquid level of the sample tube;

Step 2, open the light emitting circuit board, irradiate the liquid level of the sample tube through the exit collimation slit of the light emitting cavity of the light emitting cavity, and irradiate the light information passing through the sample tube to the incident collimation slit of the CCD receiving cavity The linear array CCD at the position, the optical information intensity is judged by the linear array CCD;

Step 3, judging the height of the liquid level of the sample tube according to the intensity of the light information, and measuring the liquid level M times to obtain an absolute height value of the liquid level of the sample tube, where M≥3.

The beneficial effects of the above technical solution are: the liquid level height is accurately measured by the above method, the data processing is fast, the frame rate is adjustable, and the data output content can be configured selectively.

In the non-contact liquid level measurement method, preferably, the step 2 includes:

Step 2-1, when the optical information intensity is judged by the linear array CCD, configure the start position in the start register of the linear array CCD as a high bit;

Step 2-2, judge the interrupt program on the optical information intensity collected by the linear array CCD, trigger the interrupt trigger on the front-end drive data acquisition module, convert the analog optical information signal into a digital optical information signal, and transmit it to the FPGA for height calculation.

The beneficial effect of the above technical solution is that the analog signal is converted into a digital signal, so that the FPGA can perform accurate high-level calculation.

In the non-contact liquid level measurement method, preferably, the step 3 includes:

Step 3-1, the liquid level height value collected is calculated in the FPGA;

Step 3-2, summing and averaging the pixels corresponding to the collected light information frame data;

Step 3-3, make a difference between the gray values of adjacent pixels, and store the difference in an array;

Step 3-4, find the position with the largest gray scale difference, and obtain the initial position of the liquid level of the sample tube;

Step 3-5, repeat step 3-2 to step 3-4, obtain M sets of data, and perform an average to obtain the absolute height value of the liquid level of the sample tube.

In summary, owing to adopting above-mentioned technical scheme, the beneficial effect of the present invention is:

1 Compact structure, strong portability, high degree of automation, easy installation and disassembly, wide applicability, can be used indoors or outdoors;

2 Non-contact measurement method, suitable for liquid level detection in workplaces with high pressure, flammable and explosive, high toxicity and high purity requirements;

3 Low power consumption, can be powered by various methods, including battery, photovoltaic, and mains;

4 Fast data processing, adjustable frame rate, optional configuration of data output content;

5. With wireless data transmission capability, the detection data can be collected on site, and can also be transmitted remotely through the wireless transmission system;

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 is the overall schematic diagram of the non-contact liquid level measurement system of the present invention;

Fig. 2 is a schematic diagram of one side of the non-contact liquid level measurement system of the present invention;

Fig. 3 is a cross-sectional schematic diagram of a non-contact liquid level measurement system of the present invention;

Fig. 4 is a schematic top view of the non-contact liquid level measurement system of the present invention;

Fig. 5 is a schematic diagram of a section of the non-contact liquid level measurement system of the present invention;

Fig. 6 is a schematic diagram of the detection circuit of the non-contact liquid level measurement system of the present invention;

Fig. 7 is a flow chart of the non-contact liquid level measurement method of the present invention;

Fig. 8 is a static detection flow chart of the non-contact liquid level measurement method of the present invention;

Fig. 9 is a flow chart of the dynamic detection of the non-contact liquid level measurement method of the present invention;

Fig. 10 is an experimental schematic diagram of the non-contact liquid level measurement system of the present invention;

Fig. 11 is a schematic circuit diagram of the non-contact liquid level measurement system of the present invention;

Fig. 12 is a schematic circuit diagram of the non-contact liquid level measurement system of the present invention;

Fig. 13 is a schematic circuit diagram of the non-contact liquid level measurement system of the present invention;

Fig. 14 is a schematic circuit diagram of the non-contact liquid level measurement system of the present invention;

Fig. 15 is a schematic circuit diagram of the non-contact liquid level measurement system of the present invention;

Fig. 16 is a schematic circuit diagram of the non-contact liquid level measurement system of the present invention;

Fig. 17 is a schematic circuit diagram of the non-contact liquid level measurement system of the present invention;

Fig. 18 is a schematic circuit diagram of the non-contact liquid level measurement system of the present invention;

Fig. 19 is a schematic circuit diagram of the non-contact liquid level measurement system of the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In describing the present invention, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientation or positional relationship indicated by "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than Nothing indicating or implying that a referenced device or element must have a particular orientation, be constructed, and operate in a particular orientation should therefore not be construed as limiting the invention.

In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be mechanical connection or electrical connection, or two The internal communication of each element may be directly connected or indirectly connected through an intermediary. Those skilled in the art can understand the specific meanings of the above terms according to specific situations.

As shown in Figures 1-5, the present invention provides a non-contact liquid level measurement system, the key of which is to include a light emitting cavity 6 and a CCD receiving cavity 14, and the light emitting cavity 6 has a light emitting cavity The body exits the collimation slit 8, and the CCD receiving cavity 14 has a CCD receiving cavity incident collimating slit 16. When the non-contact liquid level measurement system is working, the light emitted by the illuminant in the light emitting cavity 6 passes through The light-emitting cavity exits the collimation slit 8, and enters the collimation slit 16 through the CCD receiving cavity. Orientation through the sample tube.

The beneficial effects of the above technical solution are: the sample tube can be clamped through the light emitting cavity 6 and the CCD receiving cavity 14, the structure is compact and small, the portability is strong, the degree of automation is high, the installation and disassembly are easy, and it has wide applicability. Or it can be used outdoors; non-contact measurement method, suitable for liquid level detection in workplaces with high pressure, flammable, explosive, high toxicity and high purity requirements.

The non-contact liquid level measurement system preferably includes: a sample tube clamping arm, a clamping end, a hinge 3, a light emitting cavity 6, a CCD receiving cavity 14, and a rear cover of the CCD receiving cavity 15. The output collimation slit of the light emitting cavity 8, the input collimation slit of the CCD receiving cavity 16;

One end of the sample tube clamping arm is vertically fixed on the side wall of the hinge 3, and the other end of the sample tube clamping arm is provided with a clamping end, and the clamping end tightly clamps the sample tube 1, and the right leaf of the hinge 3 The leaf 21 is equipped with a light emitting cavity 6, and the left fan blade 20 of the hinge 3 is equipped with a CCD receiving cavity 14, and the rear end of the CCD receiving cavity 14 is covered by the rear cover of the CCD receiving cavity to prevent light leakage; The middle part of the side panel of the light emitting cavity 6 clamping the sample tube is in the shape of a groove, and an exit collimation slit 8 of the light emitting cavity is set along the groove shape, and the CCD receiving cavity 14 clamps the side panel of the sample tube The middle part is also in the shape of a groove, along which a CCD receiving cavity incident collimation slit 16 is set.

The beneficial effect of the above technical solution is: the liquid level of the sample tube is detected through the light emitting cavity exiting the collimating slit 8 and the CCD receiving cavity entering the collimating slit 16, which ensures the accuracy of detection and prevents light scattering , deflection.

In the non-contact liquid level measurement system, preferably, the sample tube clamping arm includes: sample tube upper clamping arm 2, sample tube lower clamping arm 9, upper clamping arm locking screw 4, lower clamping arm Holding arm locking screw 10, upper casing 28, lower casing 29;

The clamping end includes: the upper locking screw 5 of the sample tube, the lower locking screw 11 of the sample tube, the upper clamping end 12 and the lower clamping end 13;

The outer interference sleeve of the upper clamping arm 2 of the sample tube is connected to one end of the upper sleeve 28, and the side wall of the upper sleeve 28 is provided with a threaded hole, and the locking screw 4 of the upper clamping arm is screwed into the threaded hole, and the upper clamp The external thread of the locking screw 4 of the arm is matched with the internal thread of the threaded hole to lock the upper sleeve 28 and the upper clamping arm 2 of the sample tube. The other end of the upper sleeve 28 is fixed to the upper clamping end 12. A threaded hole is provided on the side wall of the holding end 12, and the locking screw 5 on the upper part of the sample tube is screwed into the threaded hole. sample tube 1;

The outer interference sleeve of the lower clamping arm 9 of the sample tube is connected to one end of the lower casing 29, and the side wall of the lower casing 29 is provided with a threaded hole, and the locking screw 10 of the lower clamping arm is screwed into the threaded hole, and the lower clamping The external thread of the arm-holding locking screw 10 is matched with the internal thread of the threaded hole to lock the lower casing 29 and the lower clamping arm 9 of the sample tube. Threaded holes are provided on the side wall of the terminal 13, and the locking screw 11 at the lower part of the sample tube is screwed into the threaded hole. Tube 1.

The beneficial effect of the above technical solution is: the above device is used to lock the sample tube, while ensuring that the sample tube is perpendicular to the bottom surface up and down, ensuring accurate measurement.

The non-contact liquid level measurement system preferably further includes: an anti-light shielding sheet 7;

The light emitting cavity 6 is installed with an anti-light shielding baffle 7 at the edge of the other end side plate of the hinge, or an anti-light shielding plate 7 is installed at the edge of the other end side plate of the hinge at the CCD receiving cavity 14 . The light-shielding mask 7 protrudes from the edge of the side plate to cover the gap where the light-emitting cavity 6 and the CCD receiving cavity 14 are joined.

The beneficial effect of the above-mentioned technical solution is: the gap between the light emitting cavity and the CCD receiving cavity 14 is blocked by the blocking effect of the light-proof blocking sheet 7, so that the external light cannot be injected, thereby ensuring the accuracy of the measurement .

In the non-contact liquid level measurement system, preferably, the hinge 3 includes: a calibration hole 23, a first calibration screw 26, and a second calibration screw 27;

The left fan blade 20 of the hinge 3 and the right fan blade 21 of the hinge 3 respectively have N calibration holes 23, and the first calibration screw 26 and the second calibration screw 27 penetrate the calibration holes 23 and screw into the side plate, according to the sample The diameter of the tube 1 is adjusted by the first calibration screw 26 and the second calibration screw 27 so that the light emitting cavity 6 and the CCD receiving cavity 14 can receive the optical feedback data smoothly, and the said N≥2.

The beneficial effect of the above technical solution is that calibration holes and calibration screws are provided on one side of the hinge where the light emitting cavity and the CCD receiving cavity are installed, so that the light emitting cavity and the CCD can be easily adjusted according to the diameter of the sample tube. The width of the gap clamped between the receiving cavities.

In the non-contact liquid level measurement system, preferably, the light emitting cavity 6 includes: a light emitting circuit board 17,

The CCD receiving cavity 14 includes: a linear array CCD18 and a CCD receiving circuit board 19;

The light-emitting circuit board 17 is installed inside the light-emitting cavity 6, and the light information emitted by the light-emitting circuit board 17 passes through the output collimation slit 8 of the light-emitting cavity, and the linear array of the CCD receiving cavity 14 CCD18 is arranged at the incident collimation slit 16 of the CCD receiving cavity to receive optical information data, and the linear array CCD is connected to the CCD receiving circuit board 19;

Described CCD receiving circuit board 19 comprises: front-end drive data acquisition module AFE, FPGA, data transmission interface, control module;

The front-end driving data acquisition module AFE is connected to the linear array CCD, receives the optical information data transmitted by the linear array CCD, and completes double sampling and AD conversion of the analog CCD image signal; the other end of the front-end driving data acquisition module AFE is connected to the FPGA, and the The FPGA connects the data transmission interface and the control module.

The beneficial effect of the above technical solution is: through the design of the above circuit, the liquid level of the sample tube can be accurately measured by means of electron optics, thereby reducing the error of manual measurement and ensuring the accuracy of measurement.

In the non-contact liquid level measurement system, preferably, the shape of the groove includes: trapezoidal or semicircular.

The beneficial effects of the above technical solution are: the trapezoidal groove is set to ensure that the light emitting cavity and the CCD receiving cavity can better hold the sample tube, and the semicircle is set to ensure that the groove and the sample tube are tightly fitted , increase the coefficient of friction to ensure that the sample tube clamped by the light emitting cavity and the CCD receiving cavity is not easy to fall off.

The invention also discloses a non-contact liquid level measurement method, the key of which is to include the following steps:

Step 1, initialize the linear array CCD and CCD receiving circuit board of the non-contact liquid level measurement system, and start measuring the liquid level of the sample tube;

Step 2, open the light emitting circuit board, irradiate the liquid level of the sample tube through the exit collimation slit of the light emitting cavity of the light emitting cavity, and irradiate the light information passing through the sample tube to the incident collimation slit of the CCD receiving cavity The linear array CCD at the position, the optical information intensity is judged by the linear array CCD;

Step 3, judging the height of the liquid level of the sample tube according to the intensity of the light information, and measuring the liquid level M times to obtain an absolute height value of the liquid level of the sample tube, where M≥3.

The beneficial effects of the above technical solution are: the liquid level height is accurately measured by the above method, the data processing is fast, the frame rate is adjustable, and the data output content can be configured selectively.

In the non-contact liquid level measurement method, preferably, the step 2 includes:

Step 2-1, when the optical information intensity is judged by the linear array CCD, configure the start position in the start register of the linear array CCD as a high position;

Step 2-2, judge the interrupt program on the optical information intensity collected by the linear array CCD, trigger the interrupt trigger on the front-end drive data acquisition module, convert the analog optical information signal into a digital optical information signal, and transmit it to the FPGA for height calculation.

The beneficial effect of the above technical solution is that the analog signal is converted into a digital signal, so that the FPGA can perform accurate high-level calculation.

In the non-contact liquid level measurement method, preferably, the step 3 includes:

Step 3-1, the liquid level height value collected is calculated in the FPGA;

Step 3-2, summing and averaging the pixels corresponding to the collected light information frame data;

Step 3-3, make a difference between the gray values of adjacent pixels, and store the difference in an array;

Step 3-4, find the position with the largest gray scale difference, and obtain the initial position of the liquid level of the sample tube;

Step 3-5, repeat step 3-2 to step 3-4, obtain M sets of data, and perform an average to obtain the absolute height value of the liquid level of the sample tube.

As shown in Figure 6, the liquid level measurement head is A: CCD receiving head; B: liquid level measurement main control board; C: data processing center, wherein the data processing center is a remote server or a portable device, etc., and the data processing center completes the displacement Data reading, storage and processing. The way of data reading, can choose wireless or wired and other ways;

Main control board structure description:

The measurement control main board is composed of four parts: the front-end drive data acquisition module AFE, the SOPC operation processing unit FPGA, the data transmission interface, and the valve control.

Among them, AFE completes the correlation double sampling and AD conversion of the analog CCD image signal;

As shown in Figure 11, it is the basic circuit of the CCD measuring head. The linear array CCDTCD1703 is connected to the CCD driving signal buffer and the CCD electrical signal output circuit, wherein the first capacitor C1 and the second capacitor C2 are connected in parallel, and one end of the second capacitor is connected to The other end of the power supply 12V is grounded, and one end of the first capacitor C1 is connected to the OD end of the linear CCD and the other end is connected to the SS end.

As shown in Figures 12 and 13, it is a CCD electrical signal output circuit, which completes the conversion of CCD serial charges to voltage signals, and is connected to the linear array CCD and AFE. One end of the first resistor R1 is connected to the power supply, and the other end is connected to the CCD electrical signal. The output terminal of the output circuit OS1, the other end of the first resistor R1 is also connected to the emitter of the first transistor Q1, the base of the first transistor Q1 is connected to one end of the third resistor R3, and the other end of the R3 is connected to the CCD electrical signal output circuit OS1 At the input end, the collector of the first transistor Q1 is connected to one end of the fifth resistor R5, and the other end of the fifth resistor R5 is grounded; one end of the second resistor R2 is connected to the power supply, and the other end is connected to the output end of the CCD electrical signal output circuit OS2, The other end of the second resistor R4 is also connected to the emitter of the second transistor Q2, the base of the second transistor Q2 is connected to one end of the fourth resistor R4, and the other end of R4 is connected to the input end of the CCD electrical signal output circuit OS2. The collector of the second transistor Q2 is connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 is grounded.

As shown in Figures 14 and 15, it is a CCD drive signal buffer 74HC245, which is used to complete the conversion of the drive signal level. It is connected to the linear CCD and the CCD electrical signal output circuit, wherein the CCD drive signal buffer includes the first CCD driver Signal buffer IC2 and the second CCD drive signal buffer IC3, wherein the VCC end of the first CCD drive signal buffer is connected to one end of the third capacitor C3 and one end of the fourth capacitor C4, the other end of the C3 and C4 is grounded, and the second CCD The VCC terminal of the driving signal buffer is connected to one terminal of the fifth capacitor C5 and one terminal of the sixth capacitor C6, and the other terminals of C5 and C6 are grounded.

As shown in Figure 17, it is the front-end drive data acquisition module AFEAD9943, which is used to complete the double sampling and analog-to-digital conversion of the CCD output signal, wherein the front-end drive data acquisition module AFE is connected to the CCD electrical signal output circuit and the main control chip FPGACON44, wherein, The output terminals of the CCD electrical signal output circuits OS1 and OS2 are connected to one end of the thirteenth capacitor C13 of the front-end drive data acquisition module AFE, and the other end of C13 is connected to the CCD input terminal of the front-end drive data acquisition module AFE, and the eleventh capacitor C11 and After the twelfth capacitor C12 is connected in parallel, one end is grounded, the other end of C11 is connected to the REFB end of the front-end driver data acquisition module AFE, the other end of C12 is connected to the REFT end of the front-end driver data acquisition module AFE, the sixteenth capacitor C16 and the seventeenth capacitor C17 After parallel connection, one end is grounded respectively to the AVSS end of the front-end drive data acquisition module AFE, the other end is respectively connected to the AVDD end of the front-end drive data acquisition module AFE and the 3.3v power supply end, and one end of the eighteenth capacitor C18 is respectively connected to the 3.3v power supply end and the front end The DRV end of the driving data acquisition module AFE, the other end is grounded, one end of the nineteenth capacitor C19 is respectively connected to the 3.3v power supply end and the DRD end of the front-end driving data acquisition module AFE, and the other end is grounded.

As shown in Figure 16, it is the motherboard DIP34*2 carrying the FPGA:

FPGA, embedded with ①noisII kernel and various user logics, including ②CCD drive timing generation logic, ③AFE related double sampling timing and output timing generation logic, ④image frame data synchronization timing generation logic, ⑤parallel image data acquisition and storage logic, ⑥liquid Bit information or image output module, ⑦Valve switch control. The logic ②-⑤ is encapsulated in the front-end driver acquisition module (as shown in Figure 6 below). This module is a self-developed logic IP.

As shown in Figure 18, it is the core board of the FPGA, which includes a CCD drive signal module and a data processing module, which are connected to the CCD drive signal buffer and the AFE module through the main board and the linear array CCD.

As shown in Figure 19, it is the communication interface MAX3232CSE, which is connected to the FPGA and the host computer, wherein RS232DB9 is connected to the communication interface, one end of the fifteenth capacitor C15 is connected to the communication interface C1+ end, and the other end of the fifteenth capacitor C15 is connected to the C1- end , one end of the fourteenth capacitor is connected to the 3.3v power supply, the other end is connected to the communication interface V+ end, one end of the twenty-sixth capacitor C26 is connected to the communication interface C2+ end, the other end of the twenty-sixth capacitor C26 is connected to the C2- end, the twenty-seventh capacitor One end of C27 is grounded, the other end of C27 is connected to the V- end of the communication interface, one end of the twenty-third capacitor C23 is grounded, the other end is connected to the VCC end of the communication interface, one end of the fourteenth resistor R14 is connected to the Tin1 end of the communication interface, and the other end is connected to the cathode of the light-emitting diode TXD , the anode of the light emitting diode TXD is connected to a power supply of 3.3v, one end of the fifteenth resistor R15 is connected to the Rout1 end, and the other end is connected to the cathode of the light emitting diode RXD, and the anode of the light emitting diode RXD is connected to a power supply of 3.3v.

As shown in Figure 7, step 1, initialize the non-contact liquid level measurement system,

Initialization task:

1. AFE configuration

2. Initialize data storage array or address

3. CCD driver module register initialization

4. Other initialization of the software system;

Step 2, start liquid level measurement, configure the start bit in the CCDSTART register to be high,

Step 3, calculating the current liquid level interface position according to a predetermined algorithm;

Extract the boundary pixel number, calculate the absolute liquid level height; output the liquid level height information.

Static measurement process:

After the measurement is started, the static liquid level measurement will go through three stages, as shown in Figure 8, which are ① front-end liquid level analog information acquisition and conversion, ② liquid level data transfer and storage in FPGA, and ③ liquid level height information obtained by algorithm operation in FPGA. With the assistance of ping-pong RAM in FPGA, ① and ② can be partially executed in parallel. ①After the ② process is completed, execute the ③ process processing.

Take the single measurement in Figure 8 above as an example to specifically illustrate the static liquid level measurement workflow. After the liquid level information in the sample tube is detected by the front-end sensor measuring head, it will output an analog video signal in high-speed serial mode. The output rate depends on the working frequency of the front-end sensor measuring head. Assuming that the working frequency is 1MHz, it will output every 1us a video signal. The sensor equipped with this liquid level measurement device is TCD1703C, which contains 7500 effective video signal units, which are evenly divided into two video interfaces for parallel output, so it takes 3.75ms for all signal output. Each video signal is converted into a 10bit digital signal through an analog front-end device, and the first stage of measurement processing is completed here. From the second stage, 3750 digital video data of one of the video interfaces are stored in the embedded ping-pong RAM of the FPGA, and the depth of the ping-pong RAM is 512. Trigger the interrupt output to the nios core. After receiving the interrupt, the nois core reads and stores the video data stored in the full RAM, and then stores the converted data in another RAM. Repeat this process until the transfer and storage of 3750 data is completed. . The focus of the third stage is to run the liquid level algorithm to obtain the liquid level height information.

Dynamic measurement process:

The dynamic measurement process is similar to the static measurement process. The difference is that if the static measurement is repeated continuously, the change information of the liquid level can be obtained. For the management and application of the liquid level change information in the sample tube, the industrial process status information can be obtained. Dynamic liquid level measurement consists of four stages: ① Front-end liquid level analog information acquisition and conversion, ② Liquid level data transfer and storage in FPGA, ③ Algorithm operation in FPGA to obtain liquid level height information, ④ Liquid level control. As shown in Figure 9.

As shown in Figure 10, it is the wave form detected by the non-contact liquid level measurement system, and the height of the liquid level is determined according to the intensity of the light.

Beneficial effects of the present invention:

1 Compact structure, strong portability, high degree of automation, easy installation and disassembly, wide applicability, can be used indoors or outdoors;

2 Non-contact measurement method, suitable for liquid level detection in workplaces with high pressure, flammable and explosive, high toxicity and high purity requirements;

3 Low power consumption, can be powered by various methods, including battery, photovoltaic, and mains;

4 Fast data processing, adjustable frame rate, optional configuration of data output content;

5. With wireless data transmission capability, the detection data can be collected on site, and can also be transmitted remotely through the wireless transmission system.

In the description of this specification, descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications, substitutions and modifications can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the invention is defined by the claims and their equivalents.

Claims (2)

1. a kind of contact-free level measuring system characterized by comprising light emitting cavity (6) and CCD receiving cavity (14), the light emitting cavity (6) has light emitting cavity outgoing collimating slit (8), and the CCD receiving cavity (14) has CCD receiving cavity incidence collimating slit (16) shines in light emitting cavity (6) when the work of contact-free level measuring system Body issue light by light emitting cavity outgoing collimating slit (8), by CCD receiving cavity incidence collimating slit (16) this Optical path enters CCD receiving cavity (14) and is received by CCD, and sample cell is in the optical path and light is to be parallel to sample cell bus Direction pass through the sample cell；

After sample cell clamping limb, clamping end, hinge (3), light emitting cavity (6), CCD receiving cavity (14), CCD receiving cavity Cover board (15), light emitting cavity are emitted collimating slit (8), CCD receiving cavity incidence collimating slit (16)；

Hinge (3) side wall vertically fixes sample cell clamping limb one end, the sample cell clamping limb other end setting clamping end, institute Clamping end fastening clamp sample cell (1) is stated, hinge (3) the right wing leaf (21) installs light emitting cavity (6), the hinge (3) left flabellum (20) installation CCD receiving cavity (14), CCD receiving cavity (14) rear end are sealed by CCD receiving cavity back shroud Lid, prevents light leakage；Light emitting cavity (6) the clamping sample cell side middle panel is groove shapes, along groove shapes Position opens up light emitting cavity outgoing collimating slit (8), and the CCD receiving cavity (14) clamps sample cell side middle panel For groove shapes, CCD receiving cavity incidence collimating slit (16) is opened up along groove shapes position；

The hinge (3) includes: calibration hole (23), the first calibration screw (26), the second calibration screw (27)；

The left flabellum of the hinge (3) (20) and hinge (3) right wing leaf (21) open up N number of calibration hole (23) respectively, by the first calibration Screw (26) and the second calibration screw (27) penetrate the calibration hole (23) and are screwed into side plate, are adjusted according to the diameter of sample cell (1) First calibration screw (26), the second calibration screw (27) connect the light emitting cavity (6) and CCD receiving cavity (14) smoothly Receive light feedback data, N >=2；

The sample cell clamping limb includes: clamping limb (9) under clamping limb on sample cell (2), sample cell, upper clamping limb lock screw (4), lower clamping limb lock screw (10), upper casing (28), setting of casing (29)；

The clamping end includes: sample cell top lock screw (5), sample cell lower part lock screw (11), upper clamping end (12) and lower clamping end (13)；

The external interference set of clamping limb (2) accesses upper casing (28) one end on the sample cell, and upper casing (28) side wall opens up Threaded hole, upper clamping limb lock screw (4) are threaded into hole, in upper clamping limb lock screw (4) external screw thread and threaded hole Screw thread matches, casing (28) and clamping limb (2) on sample cell in locking, the fixed upper clamping end of upper casing (28) other end Head (12), opens up threaded hole in upper clamping end (12) side wall, sample cell top lock screw (5) is threaded into hole, the sample Quality control top lock screw (5) external screw thread is matched with threaded hole internal screw thread, is clamped in locking end (12) and sample cell (1)；

External interference set access setting of casing (29) one end of clamping limb (9), setting of casing (29) side wall open up under the sample cell Threaded hole, lower clamping limb lock screw (10) are threaded into hole, lower clamping limb lock screw (10) external screw thread and threaded hole Internal screw thread matches, clamping limb (9) under locking setting of casing (29) and sample cell, the fixed lower clamping of setting of casing (29) other end End (13) opens up threaded hole in lower clamping end (13) side wall, and sample cell lower part lock screw (11) is threaded into hole, described Sample cell lower part lock screw (11) external screw thread is matched with threaded hole internal screw thread, locks lower clamping end (13) and sample cell (1)；

Further include: anti-light shade flap (7)；

The light emitting cavity (6) installs anti-light shade flap (7) in the edge of the other end side plate of installation hinge, or Anti- light shade flap (7) is installed in the edge of the other end side plate of installation hinge in the CCD receiving cavity (14), it is described Anti- light shade flap (7) leans out edge along side board edge, and the light emitting cavity (6) and CCD receiving cavity (14) is right The gap of conjunction state covers；

The light emitting cavity (6) includes: optical transmission circuit plate (17),

The CCD receiving cavity (14) includes: line array CCD (18) and CCD circuit board for receiving (19)；

The optical transmission circuit plate (17) is installed on light emitting cavity (6) inside, emits light by optical transmission circuit plate (17) Information passes through light emitting cavity outgoing collimating slit (8), and the line array CCD (18) of the CCD receiving cavity (14) is arranged in CCD and connects It receives at cavity incidence collimating slit (16), receives optical information data, line array CCD connects CCD circuit board for receiving (19)；

The CCD circuit board for receiving (19) includes: front-end driven data acquisition module AFE, FPGA, data transmission interface, control Module；

The front-end driven data acquisition module AFE connection line array CCD receives the optical information data of line array CCD transmission, completes mould The double sampled and AD conversion of quasi- ccd image signal；The front-end driven data acquisition module AFE other end connects FPGA, described FPGA connection data transmission interface and control module.

2. contact-free level measuring system according to claim 1, which is characterized in that the groove shapes include: ladder Shape or semicircle.